Molecular signaling is a critical therapeutic target in cancer, and molecular therapeutics have achieved some success in treating a variety of cancers. However, our incomplete knowledge of pharmacodynamic effects in vivo limits the success of these molecular therapies. We have recently developed a new molecular imaging technique, photothermal optical coherence tomography (OCT), that extends the penetration depth of high resolution molecular Imaging beyond the microscopy limit. The current proposal will further develop photothermal OCT for in vivo imaging of cell receptors, and will combine this new technique with the hemodynamic imaging capabilities of Doppler OCT and spectral microscopy to provide a comprehensive picture of the pharmacodynamic effects of molecular cancer therapies in human cells grown into tumors in the mouse window chamber. The first aim will use a combined spectral / OCT microscope lo quantify changes in metabolic rate and hemodynamics with tumor growth. The second aim will develop photothermal OCT for in vivo imaging of cell receptors, and will quantify the pharmocodynamics of receptor inhibition in the mouse window chamber. The final aim will combine OCT and microscopy to quantify longitudinal changes in receptor expression and hemodyanmic / metabolic response to combination therapies in mouse window chamber tumors. These studies will establish our novel hemodynamic, metabolic and molecular imaging techniques as high resolution, three-dimensional drug screening methods for preclinical applications. This multi-disciplinary environment will provide an excellent opportunity for professional growth and scientific advancement.